P25 with two RLT-SDR

[curvingedge]

Is it possible to use two RLT-SDR dongles to monitor a P25 Phase 1? The system frequencies are spaced too far apart for one dongle.

 

[hhca]

Yes, sdrtrunk can do this

 

[sallen07]

Is it possible to use two RLT-SDR dongles to monitor a P25 Phase 1? The system frequencies are spaced too far apart for one dongle.

And OP25 can do it with one, no matter how far apart the frequencies are, since it tunes the SDR to the voice channel and then back to the control channel (just like a scanner does).

 

[redbeard]

DSD+ will watch the CC with one dongle and follow voice with a second.

 

[Jay911]

DSD+ will watch the CC with one dongle and follow voice with a second.

I use this functionality quite well with DSD+ FastLane and two of the blue Nooelec dongles. Only thing I haven't sorted out yet is being selective on what channel(s) I want to hear. Still trying to figure out how to use priority settings to make that work.

 

[cyberwolfm636]

DSD+ has active options like clicking on the window or pressing the Space Bar to change things. I never liked the way DSD+ handled that with talk groups. I use Unitrunker 1.0 that way I can load up the Users/Groups window and put all the information in while im listening. That way I dont have to buy a subscription to this site just for a handful of talk groups. I can look them up manually and do it all to my liking. The two Dongle setup is the easy way to go. Although you can use SDRTRUNK with one dongle. I had one setup to monitor MPSCS and one setup for primary VHF frequencies our dept's still use regularly. I just bought a cheap radio scanner from ebay for analog and back to my 2 dongle unitrunker/dsd+ setup.

 

[bharvey2]

I've been doing it for several years. I used an old, dedicated Win 7 computer with an I5 processor, two NESDR Smart dongles, Unitrunker and DSD+. To be sure, it's an old setup and can be done with less now but it works just fine.

 

[cg]

Last couple versions of DSDPlus fast lane will monitor a P25 trunk system with a single dongle. You can use the second one for a second system or site.

chris

 

[redbeard]

Last couple versions of DSDPlus fast lane will monitor a P25 trunk system with a single dongle. You can use the second one for a second system or site.

chris

Of course in this configuration the dongle is leaving the control channel and you will potentially miss higher priority comms. Either way it's nice to have options.

 

[boatbod]

Of course in this configuration the dongle is leaving the control channel and you will potentially miss higher priority comms. Either way it's nice to have options.

Not necessarily. P25 allows a radio to monitor for voice grants & updates while simultaneously playing audio from a traffic channel. If the software is written well, it can use this info and tgid priority to preempt lower priority calls with higher priority traffic.

 

[redbeard]

Not necessarily. P25 allows a radio to monitor for voice grants & updates while simultaneously playing audio from a traffic channel. If the software is written well, it can use this info and tgid priority to preempt lower priority calls with higher priority traffic.

Well, I know that, but I haven't seen any evidence that DSD+ reads that voice channel data and can act on it.

 

[cg]

The higher priority traffic (lower number) takes over the single dongle from lower priority traffic.

chris

 

[maus92]

I use 2 SDRs for both DSD+ FL and Unitrunker V2. DSD+ FL is used for a Phase 2 system, and UT2 is used for a SmartZone with Phase 1 digital voice. I also use OP25 for the Phase 2 system, albeit with one SDR. The best voice quality is obtained with OP25; DSD+ FL at #2, and UT2 native Phase 1 decoding #3. Two SDRs are required for UT2 due to channel spacing.

 

[slicerwizard]

Well, I know that, but I haven't seen any evidence that DSD+ reads that voice channel data and can act on it.

I have. I use single receiver mode most of the time and I've seen how on one of our local P25 systems, while monitoring an ambulance call, DSD+ will switch to a higher priority FD call. Right in mid-sentence, the ambulance call is gone and the FD call starts coming through.

 

[redbeard]

I have. I use single receiver mode most of the time and I've seen how on one of our local P25 systems, while monitoring an ambulance call, DSD+ will switch to a higher priority FD call. Right in mid-sentence, the ambulance call is gone and the FD call starts coming through.

Good to know. I primarily use DSD+ for data gathering and not monitoring, so I have no priorities set and turn off voice following.